Airplane rudder structure



y 1934. E. J. w. RAGSDALE AIRPLANE RUDDER STRUCTURE Filed June 50, 1932 29 I {I '34 INVENTOR. 5 4 7 27 EAQLJWRAQsDALE 4* BY A {@{w fl/W A TTORNE Y.

- Patented July 24, 1934 AIRPLANE RUDDER STRUCTURE Earl I. W. Ragsdale, Norristown, Pa., assignor to Edward G. Budd Manufacturing Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 30, 1932, Serial No. 620,138

6 Claims.

The present invention relates to trussed frame structures for airfoils and particularly to an airplane rudder adapted to be formed from light gauge sheet metal by spot welding.

A special object of the invention is to obtain lightness and rigidity with a minimum amount of metal, which object is obtained by concentrating the joints of certain ones of the structural elements at a point or points of greater l0 stress thereby to utilize the extra metal necessary to produce the joint as reinforcing material and avoid the necessity of using extra metal in one part for joining,' and in another part for reinforcement.

Another object is to provide an arrangement of the component structural elements especially adapted to spot welding and arranged in a manner to give great strength with a minimum amount of material. This object is attained by a novel arrangement of the parts to utilize extended overlapping surfaces lying in different planes to form box sections at the joints and give extended surface for the making of numerousspot welds. This is permissible in spot welding because such method of welding permits the making of a lapped joint over a finished lapped joint, and the use of numerous welds or points of attachment over a large area without weakening the material as where rivet holes are required, and without additional weight as would be incident to the use of numerous rivets or an attempt to are weld over an extended surface.

Various other objects and advantages of the present invention will be apparent from a perusal of the following specification and the drawing accompanying the same.

In the drawing:

Fig. 1 is a side elevation on a small scale of the completed rudder frame.

Fig. 2 is a section on the line 2-2 of Fig. 1 showing the main rudder spar in section and one of the ribs in plan.

Fig. 3 is a detail sectional view taken on the line 3-3 of Fig. 2.

Fig. i is a perspective view of one of the hinge elements.

Fig. 5 is a fragmentary sectional view taken on the line 55 of Fig. 7, showing a hinge element in plan.

Fig. 6 is a perspective view of the joint between the rudder spar, tiller horns and the lower ribs.

Fig. 7 is a section taken on the line 7-7 of Fig. 5.

Fig. 8 is a cross sectional view taken on the line 3-8 of Fig. 5 on a slightly larger scale.

Fig. 9 is an enlarged fragmentary section on the line 5'5 of Fig. 7.

Referring to the drawing in detail, the structure consists in general of the main rudder spar 1 with a marginal member 2 defining the contour of the rudder and connected to the ends of the rudder spar 1. A second marginal member 3 defining the'contour of a smaller, forward balancing-section, is connected to the top end and upper forward side of the rudder spar. A plurality of ribs 4 connect the rudder spar 1 with the marginal member 2 and are so shaped and constructed as shown in Fig. 2, to define the surface planes of the rudder and to transmit torsion of stresses vertically through the rudder structure with a high degree of rigidity. This effect is obtained partly by constructing the ribs in cantilever form to resist lateral bending, that is to resist bending in a horizontal plane when torsion is transmitted through them vertically of the rudder structure, and is partly due to the arrangement of the ribs as a continuous lacing through the middle portion of the rudder.

A single rib 5 connects the upper central portion of the marginal member 3 with the point of juncture between the rudder spar and the lower portion of said marginal member, which rib is of a form and construction similar to that of Fig. 2, and like the ribs 4 is tapered from the rudder post to its point of attachment with the marginal member to conform to the planes of the forward extension of the rudder surfaces. The rudder is arranged to be hingedly secured to a rudder post by means of the hinge elements fi distributed along the go forward side of the rudder spar as shown in Fig. 1. For operating the rudder, a pair of tiller arms 7 (Figs. 1, 6 and 7) are secured to the rudder spar 1 near the bottom of the rudder, and in order both. to reduce the necessary amount of metal and increase the strength of the structure at the point of greatest stress, the cluster of lowermost ribs, and the lower hinge member 6 are joined to the rudder spar at the point of juncture of the tiller arms with the spar. The particular structure of this joint is shown in Figs. 6 and 7 and will be described more in detail later on.

v The rudder spar is in the form of a box section composed of a body member 8 of deep channel section closed by a cover member 9 in the form of a relatively shallow outwardly facing channel member 9 nested in the member 8 and joined by its side walls to the side walls of the member 8 by spot welding. The marginal I rudder by suitable gusset plates as indicated at and 11 in Fig. 1.

As shown in Fig. 2, the ribs are in the form of a trussed cantilever beam composed of a pair of channel section chord members 12 and 13 connected by webbing of Z-section strut elements 14. The joint between the struts and the chord member is such that the arbacent arms of the Z-section of a pair of converging strut elements, for example, the arms 15 and 16 (Fig. 3) are secured respectively to opposite side walls of the channel 13 at directly opposite points so as to bring the neutral axes of the struts and the chord member into intersection at substantially a common point. This structure renders the rib extremely rigid against twisting. The rib is further strengthened at its tapered end by a flat webbing member 17 overlapping the inner side walls of the channel section chord members and spot welded thereto, the flat web member 17 being provided for each pair of the opposed side walls of the channel section chord members. Attachment of the point of the ribs to the marginal member is effected by means'of gusset plates 18 spot welded preferably to the inner surface of the side walls of the marginal member and to the other surface of the side walls of the rib chord members, as indicated at the right hand end of Fig. 2. The ribs are joined to the rudder spar 1 by means of gusset plates 19 spot welded to the overlapping side walls of the members 8 and 9 and to the back walls of the channel section chords of the rib. This joint is further strengthened by a fiat sheet webbing member 20 spot welded to'the sides of the chord members as shown at the left of Fig. 2.

Referring to Figs. 4 and 5, it will be seen that the hinge element is composed of a' U- shaped member 21 between the arms of which is secured a hub member 22 provided with flanges 23, which serve to reinforce the hub and as attachment flanges for securing the hub to the arms of the U-shaped member 21, which attachment is efiected by means of spot welding. The arms of the U-member 21 are provided with perforations 24 registering with the pintle opening of the hub 22. Attachment of this hinge structure to the forward side of the rudder spar is effected by means of the U-shaped strap member 25 which extends around through the back of the U-member 21 and is secured to the sides of the rudder spar by spot welding.

Referring to Figs. 6 to 8 inclusive, it will be noted that the lower hinge member, the tiller horns 7 and the lowermost group of ribs converging toward the rudder spar are all secured to the rudder spar through a common joint structure in which the various parts perform the additional functions of joining elements and reinforcing elements and are arranged in a manner to form stiffening webs in box sections extending in various directions which thus makes for added rigidity and strength without undue addition of material. The tiller arms '7 are comprised mainly of side members 26 and 27 spaced apart at an angle to each other to give each arm a taper outwardly from the rudder spar, which side members are connected at-the edges by channel-section members 28 and 29 thus forming a tiller arm of closed box section. The ends of the side members 26 and 2'7 of each arm are extended laterally outward at the base of the arm to form flanges 29 and 30 overlapping a side wall of the spar 1 and directly secured thereto by spot welding. The channel member 28 extends continuously from one arm to the other across the rear face of the rudder spar 1, bearing directly against the rear or outwardly facing joined edges of the members 8 and 9 thus transmitting the load from the tiller arms to the rudder spar through the reinforced portion of the spar provided by the doublethickness of-the overlapped edges of members 8 and 9. Similarly, the edge closure member 29 extends preferably continuously from arm to arm across the forward surface of the rudder spar with the bight portion 31 of the U-shaped member 21 of the lower hinge element between the edge member 29 and the rudder spar 1, the three overlapping portions being spot welded together as indicated at 32 in. Fig. 9. For securing the lower group of ribs 2 converging toward the spar, to the spar, a pair of gusset plates 33 and 34 are secured inwardly of the overlapping edges of the spar components 8 and 9 by spot welding and extended outwardly or rearwardly of the spar to receive therebetween the ends of the ribs 2, the gusset plates overlapping the bottoms of the channel members of the ribs and being secured thereto by spot welding. Where the rib enters between the gusset plates 33 and 34, it is reinforced by a web member 35 secured to a side wall of each of the opposed chord members 12 and 13 of the rib.

For the sake of lightness, the tiller arms 7 taper in both thickness and width toward their outer ends, the ends of the side members 26 and 27 converging into contact with each other and reinforced at the end by the reinforcement elements 36 and 3'7, the four overlapping mem bers being spot welded together to form in effect. a unitary reinforced end portion. Perforations 38 are formed in these end portions to receive the pintles of suitable rudder-control cableattachments, not shown, and to bring the axes of these perforations into alignment with the axis of the opening 24 through the lowermost hinge element 6, the tiller arms 7 are inclined forwardly from their point of juncture with the rudder spar.

While a specific embodiment of the invention has been herein described for the sake of disclosure, it is to be understood that the invention is not limited to such specific embodiment but contemplates all such varients and modifications thereof as fall fairly within the scope of the appended claims.

What is claimed is:

1. An airplane rudder comprising a main rudder spar, a marginal frame member defining the contour of the rudder and connected to the ends of the spar, a plurality of rib members radiating from a common cluster joint at the spar 140 each to a separate joint at the marginal member, a pair of tiller arms secured to the rudder at said cluster joint, and means comprising a single metallic strip interconnecting" said tiller arms and abutting the rear wall of said spar. I 145 2. An airplane rudder comprising a main rudder spar in the form of a closed box section formed of a body channel section member closed by a cover member of relatively shallow channel-section nested in the body member facing 150 the rudder and connected to the ends of the spar, a pair of tiller arms secured to the spar and comprising a pair of side members, one pair for each arm, each pair secured to each of opposite sides of the rudder spar, and a transverse closure member for the rear edges of both pairs of side members extending from one tiller arm to the other around the rear flanged seams of the box-section spar.

3. An airplane rudder comprising a main rudder spar in the form of a closed box section formed of a body channel section member closed by a cover member of relatively shallow channelsection nested in the body member facing outwardly of the body member and joined by its side walls to the side walls of the body member,

a marginal member defining the contour of the rudder and connected to the ends of the spar, a pair of tiller arms secured to the spar and comprising a pair of side members, one pair for each arm, each pair secured to each of opposite sides of the rudder spar, and a transverse closure member for the rear edges of both pairs of side members in the form of an outwardly facing channel section extending from one tiller arm to the other around the rear flanged seams of the box-section spar and secured by its side walls to the inside edge portions of the tiller arm side members.

4. In an airplane rudder, a main rudder spar of thin sheet metal comprising a body channelsection member closed by a cover member attached to the body member through longitudinally extending spot welded lap seams, and a pair of tiller arms of hollow box section having their top and bottom sides secured directly to the sides of the said body channel-section; and i their rear walls comprised of a common striplike member extending from arm to arm across the rear side of the said spar and arranged .to bear directly against the said'lap seams.

5. A steering surface for aircraft comprising ,a main spar, a pair of tiller arms connected to opposite sides of said spar, said tiller arms being of hollow box section and including common front and rear wall members extending, respectively, across the front and rear wall of the spar in abutting relation therewith.

EARL J. W. RAGSDALE. 

